Control valve



Oct. 16, 1945. R. E. SCHURTZ EI'AL 2,336,317

CONTROL VALVE Filed March 8, 1941 3 Sheets-Sheet l Oct. 16, 1945. R. E. SCHURTZ ETAL 2,386,317

- CONTROL VALVE Filed March 8, 1941 l 3 Sheet-Sheet 2 A 2 W /Q 1945- R. E. SCHURTZ ETAL 2,386,817

CONTROL VALVE a 1 76 I I i fivezfiara- Patented Oct. 16, 1945 2,386,817 con'raor. VALVE Ralph E. Schurtz, Kansas City, Mo., and Joseph N. Roth, Beldlng, Mich., asslgnors, by meme assignments, to Montcalm, Incorporated, Green ville, Mich., a corporation of Michigan Application March 8, 1941, Serial No. 382,420

19 Claims.

fiuid flow paths are concentrated in a single valve unit where they terminate in ports in a cylinder, and where a valve piston or plunger is movable in the cylinder to control the fluid flow; a further feature of this invention is that the flow paths are so arranged that the fluid pressure against any surface of the valve piston in any operative position thereof is balanced by equal and opposite fluid pressure; yet another feature of this invention is that it provides a liquid seal 7 or film around a high pressure gas port to more effectively seal such port; still another feature of this invention is that it provides for bringing fluid to a temperature substantially equal to that of the valve before it contacts the valve, whereby closely fitted parts are not distorted by sudden temperature changes; other features and "advantages of this invention will be apparent from the following specification and the drawings, in which:

Figure 1 is a schematic diagram showing our invention embodied in a continuous absorption commercial refrigeration system; Figure 2 is a top plan view of the valve unit to which this application is particularly directed; Figure 3 is a vertical sectional view of the, valve unit and the top of the associated transfer chamber; Figure 4 is a horizontal sectional view along the line fl-d of Figure 3; Figure 5 is a horizontal sectional view along the line 5-5 of Figure 3; Figure 6 is a fragmentary detail view of the valve cylinder with the piston removed, the aspect being similar to that in Figure 3; Figure 7 is a view of the cylinder with the piston removed, along the line l-I of Figure 6; Figure 8 is a horizontal sectional view along the line 8-8 of Figure 3; Figure 9 is a horizontal sectional view along the line 9-9 of Figure 3; Figure 10 is a horizontal sectional view along the line l0-l0 of Figure 3; Figure 11 is a vertical sectional view along the line li-H of Figure 4; Figure 12 is a vertical sectional view along the line i2-i2 of Figure 4; and Figure 13 is a fragmentary view corresponding to Figure 3, except that the valve piston is shown in its other or upper position.

While the valve arrangement particularly illustrated and described in this application is adaptable to a number of different uses and systems,-

it has been designed for and is particularly advantageous in connection with a continuous absorption refrigeration system of the type operating at two pressures and using an intermediate transfer chamber to return rich liquor from the absorber to the still, one form of such a system being shown schematically in Figure 1. In order to better understand the operation and advantages of the control arrangement th entire refrigeration system will first be briefly described. It is to be understood, however, that the present application is directed primarily to the features of providing balanced pressures effective upon the valve piston, of providing a liquid seal around a high pressure gas port, and of precooling highpressure vapor before it reaches the valve. Other features and improvements in the refrigeration system disclosed herewith, and in the mechanical structure of the various parts, are more particularly disclosed and claimed in other copending applications, both joint and sole, which we have filed. Our earlier filed copending applications are Serial No. 296,995, filed September 28, 1939 now Patent No. 2,339,811; Serial No. 298,110, filed October 5, 1939, now Patent'No. 2,339,812; Serial No. 314,704, filed January 19, 1940, now Patent No. 2,305,640; Serial No. 319,541, filed February 17, 1940, now Patent No. 2,339,813; Serial No. 326,292, filed March 27, 1940, now Patent No. 2,339,814; serial No. 352,328, filed August 12, 1940; Serial No. 361,629, filed October 17, 1940, now Patent No. 2,339,815; Serial No. 369,876, filed December 12, 1940, now Patent No. 2,337,067 and Serial No. 380,343, filed February 24, 1941, now Patent No, 2,339,816. Copending applications filed since this application, but during its pendency, include Serial No. 388,155, filed April 11, 1941, now Patent No. 2,339,817; Serial No. 389,248, filed April 18, 1941; Serial No. 400,089, filed June 27, 1941, now Patent No. 2,354,705; and Serial No. 409,576, filed September 4, 1941;

Referring now more particularly to Figure 1 of this present application, a still i0 is adapted to contain a mixture of refrigerant and adsorbent, as ammonia and water, and is heated by any convenient means, as the burner ll, supplied with fuel through the conduit l2. Flow of fuel through this conduit is controlled by a safety device, here merely indicated schematically by the rectangle identified as I20, which is fully described and claimed in one of the above-identified applications.

Refrigerant vapor generated within the still "I passes up the pipe l3, through a water-cooled rectifier ll, to a. water-cooled condenser IS. The condensed refrigerant vapor leaves the condenser through the pipe 18 and passes up to a receiver II where an expansion valve, here illustrated as of the float-actuated type, controls the admission of vapor at greatly reduced pressure to the evaporator or cooling coils l8. These coils may be located in a large refrigeration chamber, in a store show case, or in any other desired place. The expanded refrigerant vapor leaves the evaporator through a check valve l9 and bubbles out into weak liquor in the absorber 20 through appropriate openings in the annularly arranged pipe 2|. Cooling water admitted through the pipe 22 passes through the condenser l5, through cooling coils 23 in the absorber, and through the rectifier H to its discharge line 24.

In order to keep the proper quantities and concentrations of liquor in various parts of the system it is necessary to provide a flow circuit between the absorber and the still, to deliver weak liquor to the absorber and periodically return rich liquor to the still. Since movement of liquid from the still to the absorber is from a high pressure portion to a' low pressure portion of the system, it presents no dimculties. This movement is here shown as effected by passing weak liquor out of the still through the pipe 25, passing in coils 25a through a heat exchanger 26,

and then up through a continuation of the pipe 25 to a weak liquor control valve 21. Whenever this valve is open, weak liquor driven by the high pressure in the still, passes up the pipe 25, through this valve 21, and through the pipe 28 into the open pan 28a located in the top of the absorber 20. Any excess of liquor in this pan overflows into the main body of liquor in the absorber and keeps it at the desired level. Actuation of the valve 21 to effect movement of weak liquor from the still to the absorber, and indirectly to effect return of rich liquor from the absorber to the still, is accomplished by pressure delivered,

through liquid in the pipe 29 from a thermostat bulb 30 located in the still. Pressure in the liquid actuating leg 29 is effective upon a bellows in the valve 21 to accomplish desired movement of the valve member therein. This general arrangement for control movement of weak liquor is known to the art, and will therefore not be more fully described.

The fiow path for rich liquor moving from the absorber to the still is somewhat more complex. When the level of liquid in the absorber has risen, because of the inflow of weak liquor, until it reaches the top of the pipe 3|, it drains down past the check valve 32, through another valve assembly, here identified in general as 33, and into the transfer chamber 35. A float 33 in the transfer chamber operates through snap acting mechanism located in the bottom of the transfer chamber (more fully described and claimed in another copending application to actuate the rod 31 to move the valve piston or plunger within the valve assembly 33. This valve assembly 33 is fully illustrated in Figures 2 to 13 of this application, and will be described in detail hereafter.

The valve piston has two positions in the cylinder in which it is movable, the snap action mechanism always ensuring that the valve assumes one of such two positions. In one of these positions pipe 3| opens into the transfer chamber,

as before mentioned, to permit fiow of liquid from the absorber to the transfer chamber; and gas in the transfer chamber is vented through the pipe 33 to a ring in the pan 23a whence it bubbles out into the absorber 20. When the transfer chamber 33 has filled practically to the top with liquid the upward movement of the float 33 finally throws the snap action mechanism to the position shown in the drawings, whereupon the valve piston in the valve assembly 33 moves to its upper position under the influence of the rod 31. In this upper position pipe 39, leading from the bottom of the transfer chamber, is connected through the valve unit to pipe 40, whence it flows through the heat exchanger 26 and through the pipe 4| into the still l0. It will be noted that in entering the still it passes around and in heat exchange relationship with the thermostat bulb 33, a feature more fully described and claimed in one of the above-identified applications. In order to equalize the vapor pressure in the transfer chamber with that in the still so that liquid will move from the transfer chamber to the still, a highpressure vapor connection is provided by the pipe 42. This pipe passes .through the body of liquid in the absorber and opens, through the valve assembly 33, into the top of the transfer chamber 35. I The pipes 38 and 40 provide a syphon action to drain the liquid from the transfer chamber, a i more fully described and claimed in one of the above-mentioned applications; and when the level of liquid in the chamber has dropped until the chamber is about two-thirds empty, the downward movement of the float finally causes the snap action mechanism to act through the rod 31 .to move the valve piston in the valve assembly 33 to its lower position, whereupon the transfer chamber is again placed in communication with the absorber. As soon as the system is o in a condition making another transfer action preferable, opening of the valve 21 results in a' repetition of the cycle of operations just described.

The high pressure vapor in the pipe 42 is passed through the liquid in the absorber 20 to bring it to substantially the temperature of the valve assembly 33 before it is admitted to such assembly. The vapor entering the lower end of the pipe 42 is still quite hot, having passed through the rectifier H, but not as yet having passed through the condenser i5; and it is undesirable to bring this hot vapor into contact with the valve parts. In order to insure proper sealing of fiuid pressures frequently reaching three hundred pounds to the square inch or more, it is necessary that the valve piston and the cylinder in which it moves be very closely fitted parts. It is obvious that any sudden expansion or contraction of one of these parts would throw undesired strain on it and perhaps cause suflicient distortion to cause the valve to stick. Similarly, heating of one of the members without heating of the others could cause an evenand uniform expansion, even without any distortion, sufficient to cause the valve to stick. Accordingly, the vapor is precooled by passing it in heat exchange relationship with the liquid in the absorber, so that when it enters the valve assembly it will be at a temperature substantially equal to that of such assembly.

It will be apparent from the foregoing description that a system is provided which continually boils off refrigerant vapor in the still l0,

' condenses it, and admits it at greatly reduced pressure to the evaporator or cooling coils l3 to produce the desired refrigerating effect. The rate of generation of vapor, and thus of refrigeration, can be controlled by control of the flow of fuel to the burner H. Boiling down of the concentration of liquor in the still to an undesirably low value, and raising of the concentration of liquor in the absorber to too high a value, is prevented by the periodic transfer of weak liquor from the still to the absorber and of rich liquor from the absorber, through the transfer chamber, back to the still.

As has been heretofore said, all of the novel features and improvements in a continuous absorption refrigeration system are the subject matter of other copending applications, so that attention will now be turned specifically to the construction and operation of the valve assembly 33, referring first to Figures 2 to 12, inclusive. Figures 2 to 5 and 8 to 12 show the valve piston in its lower position, and Figures 6 and 7 are fragmentary detail views of the valve cylinder with the piston removed.

The valve assembly 33 comprises as its principal parts (as may be best seen in Figures 3 and 11) upper and lower plates 55 and 56, an intermediate cylinder, and a movable valve piston or plunger 52 adapted to be moved to upper or lower position by the rod 37. The plates 5!) and 5| serve both as connector plates through which the fluid paths are completed to the cylinder, and as compression members drawn together by the bolts 53 to hold the cylinder in place. This method of holding the valve assembly together is more fully described and claimed in another copending application. For purposes of manufacturing convenience the cylinder of the valve assembly is actually composed of three concentric metal cylinders. The outer cylinder or sleeve 56 has no openings therein, and serves to close passages on the intermediate cylinder which would otherwise have to be blocked after they have been drilled clear through the walls of such cylinder. The intermediate cylinder 55 is of considerable thickness, and has all of the vertical passageways drilled therein, as may be best seen in some of the other figures. The inner cylinder,

pressure vapor pipe 42 to the'top of the transfer chamber, in order to equalize pressure in the chamber and permit the liquid to drain to the still, and this flow path will now be traced. High pressure gas (as refrigerant vapor may be termed) in the pipe 42 communicates with the vertical passageway 65 (see Figure 4). As may be best seen in Figure 8, this vertical passageway communicates with a port 86 in the cylinder wall, connected in the lower position of the valve, by an opening through the vaive, to the port 61 which is in turn connected to the vertical passageway 68. As may be best seen in Figure 3, this vertical passageway 68 opens through a connecting passageway in the plate 5| and into the top of the transfer chamber 35. In order to balance the pressure exerted against the piston by high pressure gas moving from inflow port 66 to outflow port 87, the other side of the piston is provided with a, similar passage connecting ports opening into passageways 51 and 6| (see Figure 8). Since these latter passageways have therein liquid unflowing between the ports 65 and 61.

here identified as 56, may be termed the true cylinder or port plate, since it is with the ports in this inner cylinder 55 that the valve piston 52 cooperates.

Referring now more particularly to Figures 3 and 4, it will be seen that liquid coming up from the transfer chamber through the pipe 39 is admitted to the vertical passageway 51 in the valve assembly and then passes across through the horizontal passageway at the top, here identifled as 58, to open into the upper end of the cylinder. From the upper end of the cylinder,

' which may be termed its inflow port, the liquid passes out through an annular outflow port 59, through horizontal passageway (best 'shown in Figure 5) and vertical passageway 6! to pipe 40. It will thus be seen that in the lower position of the valve liquid may flow from the transfer chamber up through the pipe 39, through inflow and outflow ports in the cylinder open to each other in this position of the valve, andthrough the pipe 40 to the still. The annular outflow passageway 59, while opening into the cylinder substantially entirely around its wall, is in reality divided into three symmetrically spaced'openings or parts of the port by the wall sections 62, 63

V and 64.

As has been mentioned before, in this position of the valve it is also necessary to connect high der the same pressure as the gas in the passageways 65 and 68, an equal and opposite pressure on the valve piston is provided. That is, sufiicient fluid under equal pressure flows through the ports 69 and T0 to balance the pressure of the gas These ports 59 and 10 are in the same plane (transverse to the axis of the cylinder) as the ports 56 and 61, and they may be termed balancing ports. In reality, part of the fluid flow from passageway 57 to passageway Si is through the top of the cylinder and the annular outflow port 59, and part of it is through the ports 69 and 10 to accomplish the desired balancing action.

It may be also noted, from references to Figure 9, that high pressure liquid in passage 5? provides fluid pressure against one side of the piston through a port, closed in this position of the valve, but balanced by equal fluid pressure against the opposite side of the piston 52, which pressure is that of the gas in the passageway 68. At the same time absorber pressure, low pressure, is effective against opposite sides of the piston 52 by reason of fluid at such absorber pressure, either gas or liquid, being present in vertical passageways H and i2. As is best seen in Figure 9, as mentioned above, port l3 communicating with passageway 51 is balanced by port 14 communicating with passageway 68, the fluid in both of these passageways being at high pressure; and port 15 communicating with passageway II is balanced by port 16 communicating with passageway 12, the fluid in both of these passageways being at low pressure. Pressure against the top of the piston by the liquid at high pressure moving from pipe 39 to pipe 40 is balanced by pressure efiective against the bottom of the piston by the high pressure gas in the transfer chamber. The only other port in the cylinder not heretofore described is the lower annular port 11, symmetrically arranged about the lower end of the piston, as may be best seen in Figure 10, this lower annular port Tl being similar in arrangement to the upper annular port 59. It is thus apparent that fluid pressure effective against any surface of the piston is balanced by equal and opposite pressure, so that there is absolutely no tendency for the valve to scrape against one side of its cylinder more than against another. In fact, the valve is amazingly free in the cylinder, and because of its balanced arrangement there is practically no wear on the parts and a perfect seal is maintained despite a large number of operations of the valve.

In normal usage, the valve will move' from upper to lower position, and back again, about once every three to five minutes.

Considering next the flowpaths provided when the valve is in upper position, as shown in Figure 13, it will be seen that pipe 3! (Figure 4) is connected to the vertical passageway II to open into the lower annular port 11 (Figure 12). with the valve in the upper position shown in Figure 13 liquid in the pipe 8| thus drains through the passageway II and the annular inflow port 11 down through the passageway 18 around the actuating rod 31, to drain into the float chamber. At the same time, upward movement of the valve has caused the openings shown in dotted lines in Figure 9 to connect the passageway H with the passageway 51, so that liquid in the pipe 3| may also drain into the transfer chamber through the pipe 39. When gas in the transfer chamber, in this position of the valve, passes up through the passageway 68 it is connected by the opening shown in dotted lines in Figure 9 to the passageway !2, thus passing out through the pipe 38 (Figure 4) and venting into the absorber to maintain pressures equalized. At the same time any lower pressure in the upper port 61 (Figure 4) operative on one side of the piston is balanced by equal pressure in the port 69 on the other side, both of these ports now being closed; the pressure at port 66 (high pressure gas) is balanced by the pressure at port (high pressure liquid), both ports being closed; high pressure fluid in the upper annular port 59 is equalized around the valve piston, this port alsobeing closed; and low pressure is effective against both ends of the piston. It will thus be apparent that in its upper position all pressure effective against any surface of the piston is again balanced by an equal and opposite pressure.

We have also included in this valve assembly means for providing an improved seal for high pressure gas, this being in the form of a groove maintaining a wall of high pressure liquid around the high pressure gas ports, between the cooperating piston and cylinder surfaces. .Referring now more particularly to Figures 6 and 7, it will be seen that the port 10 opening into the passageway 6| is surrounded by a'groove -80 in the wall of the cylinder. This groove is substantially U- shaped, with the upper ends of its legs opening into the annular high pressure liquid port 59. On the opposite side of the cylinder the port 88, opening into the high pressure gas passageway 66, is surrounded by a similar groove 8|, also opening into the annular port 59. The groove 8| is always kept full of liquid by the port 59, so that there is a high pressure liquid seal completely around the high pressure gas port 66 when it is closed by the piston being in upper position. Any pressure exerted by this groove and the liquid in it is balanced by the similar arrangement of the groove 80.

While we have shown and described certain embodiments of our invention, it is to be understood that it is capable of many modifications. Changes, therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention as disclosed in the appended claims.

We claim:

1. A valve of the character described for controlling fluid flow between the high and low pressure portions of a continuous absorption refrigeration system, including: a cylinder having inflow and outflow ports, and balancing ports opassasi'z posite each, the inflow port and its balancing port being open to fluid at the same pressure; and a valve piston movable in said cylinder to control the flow of said fluid, the piston having therein openings adapted, in one position thereof, to provide a passageway connecting the inflow and outflow ports on the one hand and a separate passageway connecting their balancing ports on the other hand, and to block all of said openings in another position thereof.

2. A valve of the character described for controlling transfer action in a continuous absorption refrigeration system wherein transfer of rich prising a plurality around the wall of liquid from a low pressure portion'of the system to a high pressure portion is effected through an intermediate transfer chamber, including: a cylinder having inflow and outflow ports, and balancing ports opposite each, the inflow port and its balancing port being open to the high pressure portion of the system; and a valve piston movable in said cylinder. to control the flow of said fluid, the piston having therein openings adapted, in one position thereof. to connect the inflow and outflow ports on the one hand and their balancing ports on the other hand.

3. A valve of the character described for controlling transfer action in a continuous absorption refrigeration system wherein transfer of rich liquid from a low pressure portion of the system to a high pressure portion is effected through an intermediate transfer chamber, including: a cylinder having inflow and outflow ports, and balancing ports opposite each, all of said ports lying in one plane transverse to the axis of the cylinder and the inflow port and its balancing port being open to the same fluid; a second set of inflow and outflow ports, and balancing ports opposite each, in another plane; and a valve piston movable in said cylinder to control flow of fluid through said ports, the piston having therein openings adapted, in at least one position thereof, to connect the inflow and outflow ports in one plane on the one hand and their balancing ports 'on the other hand.

4. A valve of the'character described for controlling fluid flow between the high and low pressure portions of an absorption refrigeration system, including: a cylinder having inflow and outflow ports, and balancing ports opposite each, the inflow port and its balancing port being open to the same fluid and all of said ports lying in one plane transverse to the axis of the cylinder; another set of inflow and outflow ports, one opening into the end of the cylinder and the other comof openings symmetrically arranged around the wall of the cylinder; and a valve piston movable in said cylinder to control flow through said ports.

5. A valve of the character described for controlling fluid flow between the high and low pressure portions of a continuous absorption refrigeration system, including: a cylinder having two sets of inflow and outflow ports therein providing two completely separate flow paths, one port of each set opening into an end of the cylinder. these ports being open to fluid at the same pressure, and the other port of each set comprising a, plurality of openings symmetrically arranged the cylinder; and a valve piston movable in said cylinder to control flow through said ports.

6. A valve of the character described for controlling transfer action in a continuous absorption refrigeration system wherein transfer of rich liquid from a low pressure portion of the system to a high pressure portion is effected through an intermediate transfer chamber, including: a cylinder member having gas and liquid'ports therein, one of the ports being open to gas at high pressure; and a piston member movable in the cylinder to control flow through said ports, one

of the members having in its wall cooperating.

with a wall of the other member a groove surrounding the high pressure gas port and connecting to a liquid port.

7. Apparatus of the character claim in claim 6, wherein the groove is in the wall of the cylinder and the liquid port to which it connects is immediately above the gas port.

8. A valve of the character described for controlling gas and liquid flow paths in a refrigeration system, including: a port member havin gas and liquid ports therein, one of the ports being open to gas at high pressure; and a valve member having a wall movably cooperating with a wall of the port member to control flow through said ports, one of the members having in one of said walls a groove surrounding the high pressure gas port and connecting to a liquid port.

9. A valve of the character described for controlling transfer action in a continuous absorption refrigeration system wherein transfer of rich liquid from a low pressure portion of the system to a high pressure portion is effected through an intermediate transfer chamber, including: a cylinder having a plurality of flow ports therein, two of said ports comprising portions of gas and liquid flow paths connecting to said transfer chamber; and a valve piston movable between two positions in said cylinder to control the flow of fluid through said flow ports, the construction of the cylinder and piston and the arrangement of the ports being such that the fluid pressures exerted upon said piston are radially and axially balanced in both positions thereof.

10. A valve of the character described for controlling transfer action in a continuous absorption refrigeration system wherein transfer of rich liquid from a low pressure portion of the sys tem to a high pressure portion is effected through an intermediate transfer chamber, including: a cylinder having a port opening into each end thereof and another port in the wall thereof adjacent each end of the cylinder and adapted to make connection with the first mentioned ports; and a valve piston movable in said cylinder to control the flow of fluid through said ports. the two end ports being connected to the top and bottom of said transfer chamber, whereby the fluid pressures exerted upon said piston are axially balanced at all times despite substantial pressure changes in the transfer chamber during transfer operations.

11. A continuous absorption refrigeration system of the character described, including: a still; a condenser, the still and condenser being adapted to operate at high pressure; an evaporator; an absorber, the evaporator and absorber being adapted to operate at low pressure; transfer means for moving rich liquid from a low pressure portion of the system to a high pressure portion, this means including a transfer chamber; and a valve unit controlling two flow paths from the transfer chamber and adapted to selectively connect said paths to the high pressure portion or the low pressure portion of the system, this unit including a cylinder and a piston movable therein, the cylinder and piston being so constructed .and arranged that the fluid pressures exerted upon said piston are radially and axially balanced in all operative positions thereof.

12. A valve of the character described for controlling transfer action in a continuous absorption refrigeration system wherein transfer of rich liquid from a low pressure portion of the system to a high pressure portion is efiected through an intermediate transfer chamber alternately connected to said low and high pressure portions, including: a cylinder; and a valve piston movable in said cylinder, the cylinder having high pressure fluid ports adjacent one end in pressure balanced relation to the piston, low pressure fluid ports adjacent the other end in pressure balanced relation to the piston, and further ports adjacent each end of the cylinder, these last mentioned ports being connectedv to the intermediate chamber and adapted to alternately conthrough'said various ports being controlled by movement of said piston.

13. Apparatus of the character claimed in claim 12, wherein said further ports open into the opposite ends. of the cylinder, whereby the piston is axially as well as radially balanced at all positions and under all pressure variations occurring in the transfer chamber.

14. Apparatus of the character claimed'in claim 12, wherein the valve cylinder includes: an inner cylindrical member adapted to have the piston movable therein, this cylinder having transverse passageways therethrough; an intermediate cylindrical member having straight transverse passageways therethrough and communieating longitudinal passageways therein, this member having its inner wall in fiuidtight relation to the outer wall of the inner member and having the transverse passageways registerin and an outer imperforate cylindrical member having its inner wall in fluidtight relation to the outer wall of the intermediate member to seal the outer ends of its transverse passageways.

15. In a continuous absorption refrigeration system having a transfer chamber, a valve operably in series connection with the chamber and adapted to connect the same alternately to low and high pressure portions of the system, said valve and chamber constituting the sole means for returning liquid from the low pressure to the high pressure portion, said valve including: a cylinder having ports therein connected to low and high pressure portions of the system; and'a ported piston therein, the construction and arrangement of ports being such that the piston is both radially and axially balanced under all operative conditions. 7

16. Apparatus of the character claimed in claim 10, including a rod connected to said piston and extending through one end of the cylinder into the chamber, said rod and piston being adapted to be moved by actuating means in the chamber.

17. A valve of the character described for controlling liquid and gas flow in a refrigeration system, including: a first member having gas and liquid ports therein, one of the'ports being open to gas at high pressure; and a second member movable with respect to and in contact with the first member to control flow through said ports, one of the members having'in its surface cooperating with a surface of the other member a groove surrounding the high pressure gas port and connecting to a liquid port.

18. Apparatus of the character described for controlling flow, in a continuous absorption refrigeration system including an absorber, both of high pressure vapor and of another fluid at a diflerent temperature, including: a valve comprising a. cylinder and a piston very closely fitted therein, the temperature of said valve and piston being affected by the temperature of the other fluid; and means for bringin the temperature or the vapor substantially to that of the valve be- 'fore the vapor reaches the valve, this means eifecting heat transfer between said vapor and said other fluid.

19. A continuous absorption refrigeration system of the character described, including: a generator; a condenser; an evaporator; an absorber; a transfer chamber for returning liquid from the absorber to the generator; operative connections between all the aforesaid portions of the system providing a plurality oi fluid flow paths, at least some of the paths having therein fluid at high pressure; and a cylinder and piston valve adapted to control a plurality of such paths, the cylinder structure comprising an inner cylindrical member adapted to have the piston movable therein, this cylinder having transverse passageways .therethrough, an intermediate cylindrical member having straight transverse passageways therethrough and communicating longitudinal passageways therein, this member having its inner wall in fluidtight relation to the other wall of the inner member and having the transverse passageways registering, and an outer imperiorate cylindrical member having its inner wall in fluidtight relation to the outer wall of the intermediate member to seal the outer ends of its transverse passageways.

- RALPH E. SCHURTZ.

JOSEPH N. ROTH. 

